Chemotactic factors generated from C5 will be carefully investigated using radiolabeled C5. This will provide drect, quantitative data regarding the chemotactic fragmentation products. The purified C5a peptide will be analyzed for its ability to act as a source for the chemotactic factor for tumor cells. Other studies in the overall project will include an investigation of the mechanisms of localization of immune complexes within tissues, particularly, and the influence of mediators on this localization process.